All magento versions contain bugs, when upgrading from one version to another you may get rid of some bugs but likely you will collect a few new ones
Magento upgrades are complex and difficult. Most take about 3 days to perform.
Below is a list of the versions and the main bugs.
126.96.36.199 has lots of checkout problems
188.8.131.52 many broken validators
184.108.40.206 admin config menus are not working